Chapter Summary
The key points covered in this chapter are as follows.
- Computer networks use signals to transmit data, and protocols are the languages computers use to communicate.
- Protocols provide a variety of communications services to the computers on the network.
- Local area networks connect computers using a shared, half-duplex, baseband medium, and wide area networks link distant networks.
- Enterprise networks often consist of clients and servers on horizontal segments connected by a common backbone, while peer-to-peer networks consist of a small number of computers on a single LAN.
- The OSI reference model consists of seven layers: physical, data-link, network, transport, session, presentation, and application.
- The OSI model layers usually do not correspond exactly to the protocol stack running on an actual system.
- The data-link layer protocols often include physical layer specifications.
- The network and transport layer protocols work together to provide a cumulative end-to-end communication service.
- The functions of the session, presentation, and application layers are often combined into a single application layer protocol.